Recently, wireless communication technology has been implemented with various measures, such as Wireless Local Area Network (W-LAN) represented by the Wi-Fi technology, Bluetooth, and Near Field Communication (NFC), in addition to connection of commercial mobile communication networks. Mobile communication services began from the voice communication-oriented first generation mobile communication service and have gradually evolved to high-speed large-capacity services (e.g., a high quality video image streaming service). It is expected that a next generation mobile communication service to be commercially available in the future will be provided through a super-high frequency band of dozens or more of GHz.
As the communication standards, such as W-LAN or Bluetooth, are vitalized, electronic devices, for example, mobile communication terminals are equipped with antenna devices operated in various different frequency bands. For example, the fourth generation mobile communication services are operated in the frequency bands of, e.g., 700 MHz, 1.8 GHz, and 2.1 GHz, WiFi is operated in the frequency bands of 2.4 GHz and 5 GHz which may be somewhat different among rules and regulations, and Bluetooth is operated in the frequency band of 2.45 GHz.
In order to provide a stable service quality in a commercial wireless communication network, a high gain and a wide beam coverage of an antenna device should be satisfied. The next generation mobile communication service is a super-high frequency band of dozens or more of GHz (e.g., a frequency band in a range of about 30 GHz to 300 GHz and a length of a resonant frequency wavelength in a range of about 1 mm to 10 mm). Thus, an antenna device, which has a better performance in terms of operating frequency than that of the antenna devices used in the mobile communication services that have been commercially available before, may be requested.
In general, as the operating frequency band becomes wider or higher, the electromagnetic waves may exhibit a strong rectilinear propagating performance and may suffer from increased loss depending on a transmission distance. In addition, due to the strong rectilinear propagating performance of the electromagnetic wave, the attenuation or reflection loss of a signal power by an obstacle (e.g., a building, or a terrain feature) may increase. Accordingly, in a communication method using a high operating frequency, localized shadow regions may appear in built-up areas. Even inside the same building, electromagnetic wave environments may vary depending on divided spaces. Accordingly, in the communication method using a high operating frequency band, the electromagnetic wave environment may be improved by changing the direction of the electromagnetic waves such that the electromagnetic waves can be transmitted to the shadow regions. As measures for changing the direction of electromagnetic waves, a dual antenna system and a reflector structure have been proposed.
The dual antenna system arranges a reception antenna at a position where the electromagnetic wave environment is good, and arranges a transmission antenna connected to the reception antenna via a transmission line so that electromagnetic waves can be delivered to a shadow region. However, the performance may be degraded due to the loss in the transmission line. Although this may be complemented by arranging, e.g., an amplifier, the addition of, e.g., a power-feeding facility is requested. Thus, there is a difficulty in arranging the dual antenna system in a built-up area or an environment having a complicated internal structure.
The reflector structure merely reflects electromagnetic waves by properly arranging reflectors formed of a conductor, and may be considerably efficiently utilized in order to eliminate shadow regions. However, since the size of a metallic structure is large, there is a difficulty in forming a proper installation environment, such as an installation position, anywhere either indoors or outdoors.